Relationship of Siblings
by YuriChan220
Summary: Futanari AU. Ayane wakes up with a surprise after touching an ancient artifact. Both of them keep it a secret from everyone. Aside from all that, while Ayane already has feelings for Kasumi, will she be able to tell her older sister how she feels? For Major Mike Powell, Leah-chan and ScaretVirus33
**Relationship of Siblings**

 **Pairing: Kasumi x Ayane**

 **Genre: Romance**

 **Disclaimer: I do not own Dead or Alive or any of its characters.**

 **Author's Note: Hello, everyone! My name is Yuri and this is my first Dead or Alive fanfic! Now, I thought about writing this story based on a 3D hentai video called "Relationship of Siblings" episodes 1 and 2, with a relationship between a younger brother and older sister (I think they're twins), but unfortunately it was not subbed, so I had to guess what's going on. And I thought I might base this hentai and make it into a Yuri based story~!**

 **Enjoy~!**

Ayane didn't want this. She never wanted it in the first place, though, she knows it's her own fault. If she hadn't touched that artifact, she wouldn't be in this situation. But there's no turning back. She needed to get more used to this "extra" part she has. Her older sister, Kasumi, has to get used to it, too, since she was with her during that mission a while ago.

The two ninjas of them sit in their room with the door closed. They are in their school uniforms and had walked together to their dorm that afternoon. Silence fills the air as Ayane sits with her back against the wall while Kasumi sits on the chair by the desk. She fiddles with her fingers while looking down. The short violet haired girl has her head down as well. None of them spoke for about a half hour now. Not that they are mad at each other or anything. Mostly because Ayane is wracking her brains on trying to strike up a conversation. But what can she say? Her heart is beating rapidly and blushing at the same time. She knows very well what those symptoms are. Love. She is in love with her older sister, Kasumi. Though, she had to keep those feelings a secret. She kept her feelings hidden for a long time now. But now that she has this "extra" part, how will she confess her feelings now? Especially when Kasumi had scolded her during their mission and found out about it.

Ayane sits there with her head down, remembering everything that happened after their mission.

 ****3 weeks ago****

 _Ayane stretched out her arms early the next morning when she noticed something sticking out from her skirt. Her eyes widened at this sight._

 _"Wh-wh-wh-what is…this!?"_ _she shrieks. Sitting up, she slowly reached her hand towards the end of her skirt. "C-c-could it be…"_

 _She lifted it up to see a penis sticking out. She gasped, quickly put her skirt back down and stood up to go to the bathroom. She knew right from yesterday when she touched the artifact that she was feeling really strange. Kasumi had warned her about it, but she was too curious to even listen to her. She approached the door and took a look at her dick. It's still sticking out and she can feel it harden. She had never felt like this before. The artifact did this to her? And how long will it last? Those were the questions that formed in her mind. However, her hand was automatically rubbing her dick. It felt…good for some reason. She doesn't know why, but her mind wanted her to do this. She rubbed and rubbed and rubbed._

 _"This is…what it feels like?" she said to herself._

 _Just then, a pair of arms wrapped around her._

 _"Guess who~?" Kasumi's voice whispered in her ear._

 _Ayane gasped and turned her head towards her. "Ah! Onee-chan!?"_

 _Kasumi was wearing a short white night dress with black thigh-high socks with her hair tied in two low pig-tails. She put a finger up to her mouth._

 _"Shhhh…" she whispers. "It's really early in the morning, you know? You'll wake the neighbors if you scream that loud."_

 _Ayane nodded. They were in their dorm after all, so the other girls next door might hear them._

 _"What are you doing out here anyways?" Kasumi asked. "If you were going to the bathroom, you should have just gone already."_

 _"U-uh…s-sure…" The violet haired girl kept her gaze averted, dodging Kasumi's eyes._

 _Kasumi frowned. "Why aren't you looking at me when I'm talking to you?"_

 _"I am looking," Ayane said._

 _"No, you're not. Your back is still turned. Is there something wrong?"_

 _"I'm fine! Just leave me-"_

 _"Shhhh…" Kasumi whispered._

 _Ayane threw her arms down. Kasumi looked at her worriedly._

 _"Ayane-chan, if there's something bothering you, you can always tell me."_

 _The violet haired girl stayed silent, looking down at the ground. Kasumi frowned and clenched her fist onto her chest._

 _"Ayane-chan, please tell me!" she said. "You're definitely hiding something, which worries me! I'm your sister, right? So, if there's anything…anything at all that you can tell me…you can say it. I'm all ears."_

 _Ayane bit her lip. She doesn't know if she should really tell the truth to her sister after discovering it. Though, Kasumi might find out anyways, so there's no other choice._

 _"Onee-chan," Ayane said. "Promise me that you won't get mad at me for this." She looked down at the floor. "I…After I touched the artifact, I felt very strange. I didn't know what it was until I woke up this morning. I…I…" She turned around, showing her penis in front of her sister. "I now have this."_

 _Kasumi gasped, cupping her hand to her mouth. "Oh, my! Wh-wh-what!? How…?" She was too speechless to comment on it. Her own sister, Ayane, now has a penis. She realized immediately what might have caused this. "I told you not to touch that!" she scolded._

 _Ayane flinched at her scolding and her eyes remained on the floor. "Onee-chan…I just couldn't help myself. That rock was just…so golden and beautiful."_

 _The ginger sighed and put her hand on her hip. "Haaaah…what are we going to do? We can't show that to the others at school. The girls will laugh at us." She gestured her hand towards Ayane's dick. "Plus that…what will the other girls think?"_

 _The violet haired girl kept her gaze on the ground. She knew she's talking about Kokoro, Lei Fang, Tina, Christie and even their senior, Helena._

 _"I…I don't know…"_

 _Kasumi exhaled slowly. "Mou~! You're making your older sister worried sick! If that's the case, you shouldn't go out in public looking like that."_

 _"N-no, I can manage!" Ayane said._

 _Kasumi leaned fowards while pointing her finger at her. "Listen, you got yourself into this mess, right?"_

 _"Y-yes…"_

 _The ginger crosses her arms with a frown on her face. "And you just HAD to touch it, didn't you? Look, I don't know how long it will last, but for now, we have to keep this a secret."_

 _"I-I guess…" Ayane looked up at her sister. "I should be able to do it! I know because I'm a strong girl!"_

 _"As you should be," Kasumi said. "So, is that a deal? To keep it a secret?"_

 _"S-sure…"_

 _The older sister smiled. "Excellent. And are you willing to live with that until we find a cure, too?"_

 _"Yes!"_

 _"Well then, for the time being, since you've got a dick now, it's time for you to learn how to use it properly~!" Kasumi winked at her with a finger in the air._

 ****End of Flashback****

Ayane shakes her head from the thought. Kasumi had taught her how to have sex using her dick and for her, it wasn't that difficult. There were a few techniques here and there, but other than that, Ayane had learned quickly from Kasumi's lessons. However, they were unable to find an antidote to Ayane's condition since 3 weeks have passed. Does that mean that she will be living with a penis for the rest of her life?

The silence is finally broken with Kasumi speaks up.

"Ayane-chan."

The violet haired girl jolts her head up. "Y-yes!?"

"Do you love me?"

Ayane nearly choked on her own saliva when she heard her say that. Did she find out about her feelings already? Or is it a sibling thing?

"Y-yes," Ayane replies. "I love you very much."

"That's good." The ginger turns her chair over towards her sister. "Then…can you prove it?"

"What do you mean?"

"You love me, right? So, let's do it."

Ayane swallows hard. "I…I don't know…"

Kasumi smirks and leans closer. "What's wrong, Ayane-chan~? Can't show me that dick of yours again?"

"I-I had enough sex since last night," the violet haired girl says as she blushes and turns away. "Can't we give it a rest for today?"

"Awww~! My own little sister is so cute like that~!" Kasumi teases. "But I'm being serious when I asked you to do it again."

Ayane slightly turns towards the ginger. She really wanted to have sex again with her sister, but after last night, she is too exhausted and needed a break. However, before she can do anything, Kasumi already crawls over next to her with a smile on her face.

"Hey…don't be shy, Ayane-chan," she whispers.

"I know…it's just…I need some time to…relax," Ayane replies.

As Kasumi sits next to her, Ayane glances at her older sister. Her beautiful facial features up close makes the violet haired girl blush even more. Then, a thought goes through her head. _Should I tell her? Is it the right time?_ For her, it's been long enough since they were together on missions, helping and protecting each other from harm. She feels ready to finally confess to her beloved sister.

However, before Ayane can say anything, Kasumi beats her to it.

"Ayane-chan," she says as she stands up. "I know you're staring at me. Is there something wrong?"

"Ah…n-no. I'm fi-WAH!" Before she can finish, she is pinned against the wall by her older sister. Her hands are against the wall and Kasumi is behind her. A hungry hand of hers slowly swoops down under Ayane's skirt until it reaches down towards her penis.

"You don't feel fine to me~," Kasumi purrs as she gives it a good rub. "You're getting hard, aren't you? From staring at my lovely body~?"

"Ah…n-no…it's…it's not like that at all…AH!" The violet haired ninja winces at the intense rubbing.

"Ohhhh, feels good, doesn't it~?"

"Ah…y-yes…it does…rub it more!"

"Hehe~! As you wish~!"

The rubbing continues, causing some more moaning from the younger sister. She needed it. She needed to feel good from her older sister.

"Ahh…ah…ahhh…yes…keep going…ahh…I-I can feel it…coming out…" Ayane moans.

And then, it is done. The semen squirts out from her dick and some of it is sprayed onto the wall. Kasumi takes a little of the leftover cum and licks it.

"See? That wasn't so hard, was it~?"

"N-no…that felt…great…"

The ginger grins as she turns her around. "Well then…let me have some more of it." She gives a few licks on Ayane's penis. And then, she allows Ayane to insert it inside her mouth and sucks on it. Soft moans come from the ginger as Ayane gently puts her hand on her head.

"Ah…yes…suck it…suck it more…" Ayane moans.

Kasumi obliges. Moans come from both of the sisters as it continues for about 2 minutes. The violet haired nina moans a bit louder.

"Onee-chan…Onee-chan…I'm gonna…ah…ahhh!"

And then, it's done. The cum squirts out inside Kasumi's mouth. The ginger pulls herself away and licks some of it off her face. Ayane pants a little as she looks over at her sister. Kasumi lying on the floor like that looks so adorable with her eyes half-open. She wants to push her down right then and there. She wants to show that she loves her older sister very much. Before Kasumi can say anything, Ayane automatically tackles her sister to the floor.

"WAH!" she cries. She lifts her head up to see her younger sister on top of her, with her ruby eyes staring into her brown ones.

Ayane gently lifts her shirt up, exposing her white bra, in which she removes shortly after admiring it. She then gently puts her hand on her breast. Kasumi winces and is about to protest when Ayane immediately pins her hand down with her other hand.

"A-Ayane…chan…?" Kasumi whispers.

The violet haired girl doesn't say anything. She keeps staring at her older sister's breasts for what it seems like minutes. And then, as if a demon had possessed her, she leans over and begins to nibble on one of her breasts, making the ginger wince.

"Ah! N-no…Ayane…ch-chan…ah!"

Ayane continues to nibble on her breast. For Kasumi, it felt good and she's glad that her beloved little sister is giving her the pleasure she wanted. The moaning continues until Ayane stops to look at her beautiful elder sister.

Kasumi gives her a gentle smile. "Hehe~! That was wonderful, Ayane-chan."

"Onee-chan. I'm sorry it hurt you when I did it." The violet haired girl averts her gaze from Kasumi's eyes.

"Don't be so silly." The ginger strokes her purple locks. "It felt great. I'm glad you took initiative to make me feel good. Now, do you want to move on to the main course?"

"Eh?" Ayane tilts her head in confusion.

Kasumi just winks at her with a smile. It is then that Ayane knows what she's trying to tell her.

* * *

The two are now on the bed. Ayane's skirt is off while Kasumi's uniform remains intact. Her skirt is lifted up so that her pussy is showing and her legs are spread out. Ayane hesitates for a few minutes, staring at her penis and Kasumi's vagina. She slowly looks up at her older sister, who just smies at her.

"Go on," she encourages her.

Ayane nods and slowly inserts her dick inside Kasumi's womanhood. The ginger winces at the tightness and moans soon after. Ayane proceeds to thrust back and forth, but very slowly, so that she gets the hang of it. Kasumi, on the other hand, moans in pleasure as the process continues. The violet haired ninja continues her routine and looks down at her older sister.

"Ah...ahh...yes...more!" Kasumi moans. "Give me more!"

"O-Onee-chan...I will! Ah..." She does her very best to make her beloved sister feel good. She thrusts her body back and forth at even a faster pace.

The moans grow louder and louder from Kasumi, begging Ayane to give her more as she goes. This goes on for another 5-10 minutes and the sisters are enjoying it all. Those lessons from Kasumi really paid off. The violet haired girl grabs both of her legs, bringing it close to her body as she thrusts back and forth, but with more force than normal.

"Hyaaahhhh~!" Kasumi shrieks. "A-Ayane-chan…you're…you're getting…ah…more intense…ahhhh~!"

"I'm gonna give it to you, Onee-chan!" Ayane says. "I'm giving you all my love, Onee-chan! Whatever it takes!" She thrusts her hips faster and faster, making the ginger moan louder.

Kasumi quickly wraps her arms around her sister and holds on for dear life as Ayane continues the process.

"This is it, Onee-chan," Ayane pants. "I'm gonna cum…"

"S-so am I…" Kasumi replies.

After a few more speedy thrusts, Ayane finally ejaculates, causing Kasumi to arch her back and scream in pleasure. Ayane arches her back as well and feels her sister's legs twitch a little. She then falls on her behind and has her back against the wall, panting. Kasumi lies on the bed, panting.

"That…felt…great…" Kasumi says, softly. She lifts her head to look at her younger sister. "What's wrong, Ayane-chan?"

"N-nothing…"

"You look a little down. You didn't enjoy our little session?"

Ayane keeps her gaze away from her sister's. "Onee-chan…I was more intense on you because I love you. I love you more than a sister." She looks up and stares at her straight in the eye. "I'm sorry I had kept my feelings hidden from you until now. I don't care if you think of me as a disgusting girl or a freak because we're both girls and sisters on top of that. But I just wanted you to know that I love you very much and…I want to be with you forever."

Kasumi blushes from her sister's confession. However, it didn't take long for her to process it so she crawls over towards her and gently puts her hands on her shoulders.

"Ayane-chan," she says, softly. "My sweet sister. I'm glad you told me your feelings. Because I feel the exact same way."

The violet haired girl blushes furiously. "Y-you do?"

Kasumi smiles as she caresses her cheek. "Of course. I would never think ill of you if you were in love with me. We've been together since we were born. We do everything together, like going on missions, train together, study together and even walk together to and from school. And I never paid attention to anyone but you. You're the only one I love, Ayane-chan."

Ayane smiles as happy tears start trickling down her cheeks. "Onee-chan…thank you! I love you so much!"

Both of them lean in and kiss. This is the most wonderful thing Ayane has experienced since the day she fell in love with her. And now her dream has finally come true. The two pull away and hug each other.

"I love you, Onee-chan," she whispers.

"I love you, too, Ayane-chan," Kasumi whispers back.

Even if Ayane has a penis, the sisters' love for each other never changed. They are by each other's side no matter what. And Ayane is happy.

* * *

 **A/N: I hope I didn't have the characters OOC, but I tried my very best. This is my very first lemon fic, and I can't help it if I'm writing AUs for my first story. So, please, give your best comments.**

 **Dedicated to: Major Mike Powell III, Dawn of Chaos and ScarletVirus33 (Nice to meet you for the first time)**


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